Fluid pump changeable in diameter, in particular for medical application

BACKGROUND OF THE INVENTION

0001The invention lies in the field of mechanics, in particular precision mechanics, and may be advantageously applied to the medical field.

0002However, independently of the application in the medial sector, applications in other fields may be envisaged, where a fluid pump is to be operated under restricted spatial conditions or at poorly accessible locations.

0003This is particularly the case with minimal-invasive medical technology, where often medical instruments or apparatus must be brought to the location of application, for example through blood vessels, with an as gentle as possible treatment of the patient. It is particularly in this context that the application of blood pumps in combination with catheters has become known, which for example may be introduced into a heart chamber whilst supporting the heart pumping activity.

0004Since a certain size is necessary for an optimised performance of such a pump, which however is limited by the diameter of the large blood vessels of the body which end in the heart, it is already known to use fluid pumps which are changeable in their radius for this purpose, which may be expanded after introduction into the heart chamber.

0005This is made possible either by way of special mechanisms, which permit an actuation of a spanning mechanism of the pump by way of a catheter or by way of the use of so-called memory materials, which may assume different shapes when changing the temperature of the surroundings, and may be brought into the desired end shape by way of temperature change.

0006However, tight limits are placed on the expansion ability of such pumps due to the necessity of accommodating a drive shaft as well as a rotor and pump housing within a small diameter.

0007In this context, it is the object of the present invention to create a fluid pump, which with as little as possible design effort, permits an as simple and as large as possible changeability of the diameter.

0008Thereby, a pump housing which is changeable in diameter as well as, as the case may be, also a rotor changeable in diameter, is provided with at least one delivery element for the fluid, as well as an actuation means running in a sleeve, in particular a pull means, at whose end which is distal seen from the introduction location of the catheter, the fluid pump is arranged.

SUMMARY OF THE INVENTION

0009The actuation means is displaceable in a longitudinal direction. The pump housing and the rotor are displaceable relative to one another by way of the actuation means in order to permit an efficient compression to a smaller diameter. This may be realised by way of either the pump housing or the rotor or both being displaceable with respect to the actuation means.

0010For example, the rotor may be moved at least partly out of the pump housing for an efficient compression of the rotor. The compression movement of the pump housing is then not limited by the rotor, which is completely accommodated in it.

0011The actuation means may for example be used as a pull means and be designed as a drive shaft, at whose proximal end a rotation drive for the pump is provided. The drive shaft in this case is rotatable and furthermore displaceable in the longitudinal direction.

0012Apart from this embodiment, there is also the possibility of driving the pump by way of an implantable miniature motor which is arranged at the distal end of the sleeve, and which is implantable into the body, or also a hydraulic microturbine. Instead of the drive shaft, the fluid pump then has its own actuation means, such as for example a cable or a wire or likewise, which displaces the rotor or other parts of the pump, in particular also pulls a bearing arrangement into the pump housing.

0013Furthermore, in the first mentioned case, there is also the possibility of applying a more suitable pull means additionally to a drive shaft. This permits the drive shaft to be optimised with regard to the demands concerning the torque transmission and running time, and permits the pull means to be optimised independently of this, with regard to the pulling function.

0014Such a pull means may for example be a cable of plastic or a wire cable or also a wire or any other suitable pull means. In the case of the use of an implantable miniature electric motor, one could for example also use the cable necessary for operation of the motor, as a pull means, and in the case of the use of a hydraulic microturbine, the hydraulic conduits or flexible tubing required for the operation of this turbine may also be used as pull means.

0015If the actuation means is stiff enough, for example is designed as wire, then a push movement may also be designed in a controlled manner. With this for example, the pump housing may also be pushed to the rotor in the longitudinal direction of the actuation means.

0016The pump housing may for example consist of an elastic framework, e.g. of a memory alloy or of a plastic, which is coated with a membrane, for example of polyurethane. The pump housing on the other hand may however also consist of segments which are moveable to one another, such as e.g. scales or lamellae which as a whole are movable and may be compressed, wherein individual scales/segments or lamellae may be stiff per se or flexible. The rotor, as the case may be, is compressible per se by way of the fact that either individual delivery elements of the rotor may be folded or pivoted onto the shaft for reducing the diameter, or the fact that the rotor consists of a membrane which may be stretched out by way of one or more tautening elements.

0017Additionally to the outlined embodiments of the pump housing and the rotor, also other compressible and expandable construction shapes are conceivable for the application of the invention.

0018It is advantageous for a particularly good compressibility of the arrangement, if the pump housing and the rotor are displaceable to one another so far in the longitudinal direction of the actuation means, that they may be arranged behind one another in the longitudinal direction, or with a mutual overlapping in the longitudinal direction, which is smaller than the overlapping during the operation of the fluid pump. The different parts thereby may be displaceable on a drive shaft, which either forms the actuation means or whose extension is in the region of the pump, if an implantable miniature motor is provided at the end of the sleeve.

0019A particularly advantageous embodiment of the invention envisages a bearing arrangement being arranged on the actuation means or its extension, at the distal end of the actuation means or its extension, behind the rotor seen from the rotation drive.

0020One achieves a particularly quiet and smooth running of the rotor by way of a further mounting at the distal end of the pump housing being provided additionally to a mounting at the proximal end of the pump housing. The respective bearing arrangement may likewise be movable relative to the pump housing within the framework of the invention. It is advantageously displaceable on the actuation means or its extension, in their longitudinal directions, or at least displaceable with the actuation means or the extension, with respect to the rotor and the pump housing, as long as the actuation means itself is displaceable in the longitudinal direction.

0021After the expansion of the fluid pump device, the bearing arrangement may be brought by way of this to its location of application at the distal end of the pump housing, by way of a further displacement movement.

0022A further advantageous design of the invention envisages the bearing arrangement being displaceable relative to the rotor in the longitudinal direction of the actuation means.

0023With this, the bearing arrangement as well as the rotor may be compressed and expanded independently of one another and be displaced to one another in the longitudinal direction only after the attachment of the fluid pump device, in order to achieve the operating arrangement.

0024If the bearing arrangement is axially displaceable to the actuation means or the extension, then an abutment body should be provided on these, for example at their end which on pulling back the actuation means, entrains the bearing arrangement in the direction of the activation device.

0025The bearing arrangement for its part may then abut against the rotor and also move this in the direction of the pump housing up to the end position.

0026One may also envisage the bearing arrangement being movable with the rotor into the inside of the pump housing, and struts arranged in a star-like manner being provided, which elastically brace between a hub of the bearing arrangement and the pump housing.

0027This may advantageously be achieved by way of the struts being elastically pivotably fastened on the hub of the bearing arrangement.

0028For this purpose, the struts just as the bearing arrangement, may for example consist of an elastic plastic or rubber, or of a spring-elastic metal.

0029It may also be advantageous for the struts to be radially extended by way of folding open in the course of the movement of the drive shaft, by way of axial compression of the bearing arrangement. This e.g. is possible if the bearing arrangement comprises two rings which are mutually to one another in the axial direction, between which the struts are fastened, wherein the struts bear in a flat manner given a larger distance of the rings, and are expanded in a bead-like manner with a pushing-together of the rings.

0030The struts in the braced condition may advantageously form an inflow cage at the distal end of the fluid pump, which on the one hand prevents the rotor from coming into contact with body tissue and one the other hand ensures that any larger coagulated masses, which are located in the fluid to be delivered, may not penetrate into the pump housing.

0031Moreover, it is advantageous to design the actuation means in a displaceable manner with respect to the sleeve in the longitudinal direction, in particular to the rotation drive at the proximal end of the sleeve, in order to effect the different axial displacement movements of the pump housing, the rotor and the bearing arrangement to one another.

0032The sleeve thereby is usually designed as a catheter in the field of the medical application. Such a catheter although being flexible, is also so stiff that it may be pushed through a blood vessel. The catheter is usually connected to the pump housing in a fluid-tight manner, wherein the actuation means, for example a drive shaft, is introduced in an as sealed as possible manner into the pump housing through a rotation lead-through.

0033The catheter, at the proximal end which usually lies outside the body of the patient, is connected in a fluid-tight manner to an actuation device and for example also to an electromotoric drive, inasmuch as no implanted micro-motor is preferred in the region of the fluid pump.

0034Advantageously, the catheter is filled with a body-compatible fluid, for example a saline solution, in order on the one hand to prevent the penetration of gas bubbles into the body and on the other hand, as the case may be to lubricate and cool the shaft which usually rotates at 20,000-35,000 revolutions per minute.

0035The present invention in the case that it is provided within the sleeve of a drive shaft, may further advantageously be designed such that the drive-side end of the drive shaft is connected to a drive body which is arranged in a sealed housing and which may be driven in a magnetic and rotatory manner from outside the housing.

0036This embodiment permits the drive of the drive shaft through a magnetically inactive housing, without a rotation lead-through which is to be sealed off, by way of a rotation field being applied, which sets the drive body located in the housing and thus the drive shaft, into rotation.

0037A displacement ability of the drive shaft in the longitudinal direction according to the invention is achieved by way of the drive body being displaceable in the longitudinal direction of the drive shaft, and being driven on the cover side by way of a changing magnetic field.

0038Due to the cover-side transmission of the drive forces, this is independent of an axial displacement of the drive body on pulling or pushing the shaft.

0039However, one may also envisage the drive shaft being connected in a fixed manner to a catch body, which for its part is displaceably guided in a direct manner in the rotor in the longitudinal direction of the drive shaft.

0040In this case, the drive body is arranged in a stationary manner in the axial direction of the drive shaft, and only a catch body which is connected to the rotor in a rotationally fixed manner, for its part is axially displaceable with the drive shaft. Such a catch body may for example be designed as a body which is polygonal in cross section, for example an octagonal body.

0041The invention apart from a fluid pump device of the initially mentioned type, also relates to a method for operation of such a device, wherein one envisages the fluid pump device in the compressed condition being brought to a location of application, thereafter at least partly expanding the pump housing and thereafter displacing the pump housing and the rotor to one another in the longitudinal direction of the actuations means, in particular of a drive shaft of the rotor, such that the rotor is completely accommodated in the pump housing.

0042A greater compression of the individual parts by way of their staggering in the longitudinal direction of the actuation means is possible with the mentioned method steps, specifically by way of firstly the individual elements of the pump housing, the rotor and the bearing arrangement being brought to the application location, thereafter at least partly expanded and only after this being brought into the constellation necessary for operation by way of relative axial displacement.

0043After the introduction of the arrangement for example into the body of a patient, with the means of the invention, one may for example retract the drive shaft, and thus the bearing arrangement as well as the rotor may be moved in the direction of the pump housing, until the rotor is located completely in the pump housing and is supported by the bearing arrangement as the case may be.

0044As to whether the rotor is expanded before or after it is introduced into the pump housing is neither here nor there, just as is the case with the possibility of only partly expanding the pump housing as much as is necessary firstly before the introduction of the rotor, in order to introduce the rotor, or whether the pump housing is completely expanded already before the introduction of the rotor.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

0045The invention is hereinafter shown and described hereinafter by way of one embodiment example in a drawing. Thereby, there are shown in:

0046<figref idref="DRAWINGS">FIG. 1</figref> a schematic overview of a fluid pump device, wherein the pump is inserted into a heart chamber,

0047<figref idref="DRAWINGS">FIG. 2</figref> a three-dimensional picture of a pump rotor,

0048<figref idref="DRAWINGS">FIG. 3</figref> a lateral view of the pump housing, of the rotor and of a bearing arrangement,

0049<figref idref="DRAWINGS">FIG. 4</figref> a lateral view of the pump housing with a rotor located therein,

0050<figref idref="DRAWINGS">FIG. 5</figref> a detail of the pump housing in a three-dimensional representation,

0051<figref idref="DRAWINGS">FIG. 6</figref> a bearing arrangement of <figref idref="DRAWINGS">FIG. 6</figref> in a front view,

0052<figref idref="DRAWINGS">FIG. 7</figref> the bearing arrangement of <figref idref="DRAWINGS">FIG. 6</figref> in a front view,

0053<figref idref="DRAWINGS">FIG. 8</figref> a further bearing arrangement,

0054<figref idref="DRAWINGS">FIG. 9</figref> a bearing arrangement as from <figref idref="DRAWINGS">FIG. 8</figref>, in a compressed condition,

0055<figref idref="DRAWINGS">FIG. 10</figref> a further bearing arrangement in a lateral view,

0056<figref idref="DRAWINGS">FIG. 11</figref> the proximal end of a drive shaft with a coupling to a rotation drive, and

0057<figref idref="DRAWINGS">FIG. 12</figref> another design of the proximal shaft end, with another coupling to a drive.

DETAILED DESCRIPTION OF THE INVENTION

0058<figref idref="DRAWINGS">FIG. 1</figref> shows a heart chamber, which is connected to a blood vessel <b>2</b>, into which blood is to be pumped. For supporting the pump activity, a fluid pump <b>3</b> is introduced into the heart chamber <b>1</b>, which there sucks blood and pumps this into the blood vessel <b>2</b>.

0059A catheter <b>4</b> is introduced through a lock <b>5</b> into the blood vessel <b>2</b>, through which lock the catheter may also be pulled out again. The catheter <b>4</b> at its distal end carries the pump <b>3</b> in the form of a pump housing <b>6</b> connected to the catheter, and a rotor <b>7</b>. The rotor <b>7</b> is rotatably mounted on a drive shaft <b>8</b> and comprises delivery elements, which on rotation suck the blood in the direction of the arrows <b>9</b> or eject it in the direction of the arrows <b>10</b> into the blood vessel <b>2</b>. For this, the delivery elements in the shown representation, which shows the explained position of the fluid pump, have a helically arranged delivery blade surface.

0060The construction of the pump housing and the rotor will be dealt with in more detail further below.

0061The drive shaft <b>8</b> is driven by the drive <b>11</b>, which is accommodated in a housing <b>12</b>. The drive elements are only schematically shown in <figref idref="DRAWINGS">FIG. 1</figref> and are explained further below likewise, in a more detailed manner.

0062<figref idref="DRAWINGS">FIG. 2</figref> in detail shows a pump motor with two helical delivery blades <b>13</b>, <b>14</b>, which are offset to one another by 180° on the periphery of the drive shaft <b>8</b>. The individual delivery blades consist of spanning elements such as for example struts <b>13</b><i>a</i>, <b>13</b><i>b</i>, as well as a frame <b>13</b><i>c </i>which is tautened with a membrane, for example of polyurethane or polyethylene. The frame and the struts may for example consist of a memory material which assumes its shape dependent on temperature. Then in a compressed form at a first temperature, preferably cooled, such a pump rotor may be introduced into the body of the patient and there may automatically unfold or expand after heating to the body temperature or subsequent further heating.

0063However, it is also conceivable to automatically erect the pump rotor by way of a rotation drive in the operation direction, by way of the fluid to be delivered, thus blood in this example, catching in the delivery blades and leading to an erection of the delivery blades by way of the counter pressure of the fluid.

0064The constructional shape of the rotor may also differ from that which has been described above, by way of using collapsible or pivotable elements, in order to form a delivery blade surface. The pivotable parts may then usefully be folded onto the drive shaft in the compressed condition.

0065The struts <b>13</b><i>a</i>, <b>13</b><i>b </i>as well as the frame <b>13</b><i>c </i>of the pump housing are usefully tautened, but the frame <b>13</b><i>c </i>runs in the direction of the pump housing somewhat beyond the tautening and forms a run-in chamfer there, which serves for a simpler displacement of the rotor into the pump housing.

0066<figref idref="DRAWINGS">FIG. 3</figref> shows a pump housing <b>6</b>, a rotor <b>7</b> as well as a bearing arrangement <b>15</b>, which are distributed distanced to one another axially on the drive shaft <b>8</b>. This condition remains at least until the mentioned parts are brought within a body of a patient on location.

0067Thereafter, the drive shaft <b>8</b> may be retracted in the direction of the arrow <b>15</b>, in order to form a functioning construction unit of a fluid pump by way of a relative displacement of the rotor, pump housing and bearing arrangement.

0068On pulling-back the drive shaft <b>8</b>, firstly the catch <b>17</b> abuts the hub <b>18</b> of the bearing arrangement <b>15</b>. With a continued pulling-back of the shaft, the bearing arrangement is carried along and is pressed against the rotor <b>7</b>. This is likewise carried along and, with the continued pulling back of the drive shaft <b>8</b>, is pulled into the inside of the pump housing <b>6</b>. Thereby, the rotor <b>7</b> moves so far into the pump housing, until it is completely covered by this.

0069The pump housing <b>6</b> at its open end carries a fixation ring <b>19</b>, in which the struts of the bearing arrangement <b>15</b> may clamp.

0070<figref idref="DRAWINGS">FIG. 4</figref> shows the pump housing, the rotor and the bearing arrangement in an axially pushed-together form. The fixation ring <b>19</b> is described in more detail in <figref idref="DRAWINGS">FIG. 5</figref>. It consists of two individual rings <b>19</b><i>a</i>, <b>19</b><i>b </i>which are also coaxially positioned to one another and are connected by way of connection bars which are like ladder rungs. In each case, the ends of the struts <b>20</b>, <b>21</b> of the bearing arrangement <b>15</b> have space between the connection bars <b>19</b><i>c</i>, <b>19</b><i>d</i>, so that after the introduction, the bearing arrangement is radially centred there as well as axially positioned with respect to the ring <b>19</b>. The bearing arrangement is shown schematically in <figref idref="DRAWINGS">FIG. 6</figref> and comprises a hub <b>18</b> and struts <b>20</b>, <b>21</b>. The struts <b>20</b>, <b>21</b> are pivotably movably fastened on the hub <b>18</b> either by way of a joint or by way of their flexibility.

0071If the bearing arrangement is displaced with respect to the pump housing by way of pulling back the drive shaft, then the ends of the struts <b>20</b>, <b>21</b> are applied elastically into the compartments between the bars <b>19</b><i>c</i>, <b>19</b><i>d </i>of the ring <b>19</b>. There, the bearing arrangement braces automatically and centres the drive shaft mounted in its hub, with respect to the pump housing <b>6</b>.

0072<figref idref="DRAWINGS">FIG. 6</figref> shows a long bearing arrangement, with which in each case a significantly long hub piece is arranged in front of as well as axially behind the struts. The bearing arrangement may also be constructed in a shorter manner by way of a hub only being provided on one side of the struts, as is shown in <figref idref="DRAWINGS">FIG. 8</figref>.

0073<figref idref="DRAWINGS">FIG. 7</figref> shows a front view of the bearing arrangement of <figref idref="DRAWINGS">FIG. 6</figref>

0074<figref idref="DRAWINGS">FIG. 9</figref> shows the movement ability of the struts in the compressed condition.

0075On introducing the fluid pump device through a blood vessel into a human body, the struts <b>20</b>, <b>21</b> firstly bear snugly on the hub body, as long as the bearing arrangement is still located within the vessel, and is then elastically expanded. This elasticity after the expansion and the axial contraction of the pump elements ensures that the bearing arrangement remains fixed in the ring <b>19</b> of the pump housing.

0076<figref idref="DRAWINGS">FIG. 10</figref> shows a further embodiment of the bearing arrangement with a double shaft mounting and specifically in the region of the bearing <b>22</b>, <b>23</b>. The struts are formed and radially extended by way of two hub parts <b>22</b>, <b>23</b> of the bearing arrangement approaching one another by way of axially pulling on the drive shaft. The struts on approaching the two hub parts are folded open on one another in a bead-like manner and extend radially away from the drive shaft. With an adequate expansion, these struts may also brace themselves in the ring <b>19</b>.

0077<figref idref="DRAWINGS">FIG. 11</figref> shows the proximal end of the shaft <b>8</b> and its coupling to a drive, which is to permit an axial displacement ability of the drive shaft by 10 to 14 mm, in order after the introduction of the individual elements of the fluid pump to the application location, to be able to pull back the bearing arrangement and the rotor into the pump housing by way of pulling back the drive shaft.

0078<figref idref="DRAWINGS">FIG. 11</figref> in this context represents a gas-tight coupling of the catheter <b>4</b>, which forms the sleeve for the shaft <b>8</b>, onto a fluid-tight housing <b>24</b>. A drive body <b>25</b> is located in the housing <b>24</b> and has magnet elements <b>26</b>, <b>27</b> on its periphery, which on the cover side may be driven in a changing magnetic field incorporated outside the housing <b>24</b>. A drive movement is transmitted by way of this in a simple manner via the fluid-tight wall of the housing <b>24</b>. For example, a second drive body <b>28</b> with permanent magnets or electric magnets may rotate outside the housing <b>24</b>, or windings may be arranged there, which produce a rotating field.

0079A bolt <b>30</b> is fastened on the base <b>29</b> of the housing <b>24</b> and carries a thread <b>31</b> which is stationary in the axial direction.

0080The rotor <b>25</b> carries a ring <b>32</b> with an inner thread which runs on the thread <b>31</b>.

0081With a rotation of the drive body <b>25</b> in the operating direction, by way of the cooperation of inner and outer thread, the drive body <b>25</b> is moved in the direction of the arrow <b>33</b>, by which means the drive shaft <b>8</b> is pulled back. The inner ring <b>32</b> after completion of the retraction movement of the shaft runs away from the thread <b>31</b>, and as a result the drive body <b>25</b> may rotate axially in a stationary manner. The fluid pump is thus axially pushed together and set into operation.

0082<figref idref="DRAWINGS">FIG. 12</figref> shows another embodiment at the proximal end of the drive shaft <b>8</b>. In the representation of <figref idref="DRAWINGS">FIG. 12</figref>, only the magnets <b>26</b>, <b>27</b> of the drive body <b>25</b> which are located within a fluid tight housing <b>34</b> are represented. The drive body <b>25</b> may be mounted in the housing in an axially stationary manner and is driven in a rotational manner from the outside. It transmits the rotation movement onto a polygonal piece <b>35</b>, which is guided in a complementarily shaped opening (lock) <b>36</b> in the drive body in a rotationally fixed manner, but axially displaceable manner with respect to this. For example the lock <b>36</b> and the polygonal piece <b>35</b> may be designed as a regular octagonal bolt, square bolt or hexagonal bolt.

0083The drive shaft <b>8</b> is connected in a rotationally fixed manner in its end region <b>37</b> to a bush <b>38</b>. An armature <b>39</b> is rotatably received in the bush <b>38</b> with an undercut, and the armature does not rotate with the bush <b>38</b>, but axially fixed this. The armature <b>39</b> is provided with a ring <b>40</b> through which a pull tape <b>41</b> is pulled. If the armature <b>39</b> is pulled back manually in the direction of the arrow <b>42</b> by way of the pull tape <b>41</b>, then the armature pulls the bush <b>38</b>, which may rotate with respect to the armature, in the direction of the arrow <b>42</b> a little out of the catheter <b>4</b>, so that the necessary displacements may take place in the region of the fluid pump. The drive body <b>25</b> may be driven during this without upsetting the pulling movement.

0084The armature <b>39</b> may be fastened in a fluid-tight manner to the housing <b>34</b> by way of a bellows or a sealingly connected membrane <b>43</b>, in order to ensure the sealedness of the housing <b>34</b>.

0085Thus, an efficient manner of the drive with a displacement ability of the drive shaft is provided by way of the invention, wherein the displacement of the drive shaft, for completing the fluid pump after introduction to the place of operation, is used in an optimal manner by way of an axial relative displacement of the rotor, bearing arrangement and pump housing.